Gene Therapy Research
Christopher J. Etheridge (e-mail: c.etheridge@ic.ac.uk)
Post-doctoral research assistant - Gene therapy
Luisa Stewart (e-mail: l.stewart@ic.ac.uk)
3rd year PhD student - Gene therapy
Imran Shah (e-mail: sayyed.shah@ic.ac.uk)
1st year PhD student - Gene therapy
Gene therapy could revolutionise medicine in the next century! In short, gene therapy may be defined
as the delivery of nucleic acids to patients, by means of a vector, in order to bring about therapeutic
benefit. Gene therapy therefore not only covers the delivery of therapeutic genes but also antisense
DNA, RNA and other nucleic acid constructs. Vectors in current use are either viral or non-viral. We
are developing the use of non-viral cationic liposome based vector systems. Previously in the group,
cationic liposomes were formulated using the neutral, zwitterionic lipid
dioleoylphosphatidylethanolamine (DOPE) and the cationic lipid (cytofectin) 3b-[N-(N',
N'-dimethylaminoethane)carbamoyl]cholesterol (DC-Chol) , and then used by our collaborators to
deliver a correct cystic fibrosis transmembrane conductance regulator (CFTR) gene into the lungs of
transgenic mice suffering artificially from cystic fibrosis. The mice were cured of cystic fibrosis thereby
providing one of the first proofs of principle of gene therapy using a non-viral vector system.
However, it was clear at the conclusion of the mouse cystic fibrosis experiments, that the
DC-Chol/DOPE liposomes would not work well enough to function as a vector for the delivery of correct
CFTR genes into the lungs of human cystic fibrosis patients. Therefore, a programme of organic
synthesis was begun to prepare polyamine analogues of DC-Chol which were then formulated into
liposomes with DOPE and evaluated for gene delivery efficiency in vitro and in vivo. Results have been
good and at least one novel polyamine analogue of DC-Chol has been identified which was at least
100-fold more efficient at mediating gene delivery in vivo than DC-Chol itself. This analogue should be
good enough for efficient gene delivery into the lungs of human beings. You will be able to read about
this soon!
We are now preparing cationic liposome vectors which will selectively target different body organs, so
as to deliver potential therapeutic genes into the heart, brain and joints, to name but a few organs of
interest to us. In addition, we are also closely studying the formation of cationic liposome/DNA
complexes using spectroscopic techniques which include fluorescence, photon correlation spectroscopy
and fluorescence correlation spectroscopy. We hope ultimately to be able to correlate the gene delivery
efficiencies of liposomes containing our novel DC-Chol analogues with the observed physical properties
of these liposomes and their complexes with DNA. In this way, it should be considerably easier to make
rational improvements in cationic liposome vector systems in future.
Recently, we have also had some success with the design of two-domain peptides containing an
oligo-L-lysine moiety attached to a cyclic RGD (arginine.glycine.aspartic acid) peptide moiety. The
former moiety binds DNA whilst the latter targets the bound DNA for cell entry via an integrin-receptor
binding mechanism.
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